Friday, December 10, 2010

Linearly Polarized Modes of a Corrugated Waveguide

E.J. Kowalski et al., Linearly Polarized Modes of a Corrugated Waveguide, IEEE Trans. on Mic. Theo. and Tech., 2010, 58(11), 2772-2780


A linearly polarized $({rm LP}_{mn})$ mode basis set for oversized, corrugated, metallic waveguides is derived for the special case of quarter-wavelength-depth circumferential corrugations. The relationship between the ${rm LP}_{mn}$ modes and the conventional modes $({rm HE}_{mn},{rm EH}_{mn},{rm TE}_{0n},{rm TM}_{0n})$ of the corrugated guide is shown.
The loss in a gap or equivalent miter bend in the waveguide is calculated for single-mode and multimode propagation on the line. In the latter case, it is shown that modes of the same symmetry interfere with one another, causing enhanced or reduced loss, depending on the relative phase of the modes. If two modes with azimuthal $(m)$ indexes that differ by one propagate in the waveguide, the resultant centroid and the tilt angle of radiation at the guide end are shown to be related through a constant of the motion. These results describe the propagation of high-power linearly polarized radiation in overmoded corrugated waveguides.